high-performance photodetection is highly desirable in various fields, including optical communication, imaging, and environmental monitoring. [4][5][6] Currently, GaN, Si, InGaAs, and other semiconductors have dominated the ultraviolet to near-infrared photodetection market. [7][8][9][10] These detectors are mostly assembled on rigid substrates and usually require relatively thick active materials for photonic detection, therefore, they are not compatible with flexible systems or suitable for low cost manufacturing.The demand for flexible devices has driven the research in emerging functional materials that are bendable. To date, various functional materials have been explored for constructing flexible photodetectors, such as zero-dimensional (0D) semiconductor nanostructures, 2D layered materials, and perovskites. [11][12][13][14] They can be facilely transferred to arbitrary rigid substrates and directly deposited on flexible substrates, which are favorable for flexible optoelectronics. Particularly, organometal halide perovskites (OHPs) have demon strated intriguing properties, including large absorption coefficients, tunable bandgaps, long carrier diffusion length, and high carrier mobility. [15][16][17][18][19][20] Nevertheless, their organic parts Flexible devices are garnering substantial interest owing to their potential for wearable and portable applications. Here, flexible and self-powered photodetector arrays based on all-inorganic perovskite quantum dots (QDs) are reported. CsBr/KBr-mediated CsPbBr 3 QDs possess improved surface morphology and crystallinity with reduced defect densities, in comparison with the pristine ones. Systematic material characterizations reveal enhanced carrier transport, photoluminescence efficiency, and carrier lifetime of the CsBr/KBr-mediated CsPbBr 3 QDs. Flexible photodetector arrays fabricated with an optimum CsBr/KBr treatment demonstrate a high open-circuit voltage of 1.3 V, responsivity of 10.1 A W −1 , specific detectivity of 9.35 × 10 13 Jones, and on/off ratio up to ≈10 4 . Particularly, such performance is achieved under the self-powered operation mode. Furthermore, outstanding flexibility and electrical stability with negligible degradation after 1600 bending cycles (up to 60°) are demonstrated. More importantly, the flexible detector arrays exhibit uniform photoresponse distribution, which is of much significance for practical imaging systems, and thus promotes the practical deployment of perovskite products.The "Internet of Things" (IoT) has been expected to reshape or even revolutionize human daily lives. As a fundamental technology of the IoT, flexible optoelectronics, such as solar power sources, display panels, and photodetectors, have attracted substantial research interest globally. [1][2][3] Moreover,

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.201905362. Fluorescence imaging with photodetectors (PDs) toward near-infrared I (NIR-I) photons (700-900 nm), the so-called "optical window" in organisms, has provided an important path for tracing biological processes in vivo. With both excitation photons and fluorescence photons in this narrow range, a stringent requirement arises that the fluorescence signal should be efficiently differentiated for effective sensing, which cannot be fulfilled by common PDs with a broadband response such as Si-based PDs. In this work, delicate optical microcavities are designed to develop a series of bionic PDs with selective response to NIR-I photons, the merits of a narrowband response with a full width at half maximum (FWHM) of <50 nm, and tunability to cover the NIR-I range are highlighted. Inorganic halide perovskite CsPb 0.5 Sn 0.5 I 3 is chosen as the photoactive layer with comprehensive bandgap and film engineering. As a result, these bionic PDs offer a signal/ noise ratio of ≈10 6 , a large bandwidth of 543 kHz and an ultralow detection limit of 0.33 nW. Meanwhile, the peak responsivity (R) and detectivity (D*) reach up to 270 mA W −1 and 5.4 × 10 14 Jones, respectively. Finally, proof-ofconcept NIR-I imaging using the PDs is demonstrated to show great promise in real-life application.Near-infrared photodetectors (NIR PDs) toward distinct photon signal from 700-900 nm (NIR-I) have attracted much attention in the past decades due to their tremendous potential in medical instruments. [1] Benefitting from merits including low

Kesterite Cu2ZnSnS4 (CZTS) has attracted attention as an earth-abundant alternative to commercially successful CIGS solar cells. CZTS exhibits decent optoelectrical properties while having excellent stability on top of being an earth-abundant, low-cost and non-toxic material. Therefore, in recent years, there has been a significant research effort to develop CZTS-based devices. The efficiency of CZTS solar cells reached 12.6% in 2013, and this was a remarkable achievement at the time. However, the efficiency of these devices has been stagnant since then while emerging technologies, most notably perovskite solar cells, keep breaking record after record. Currently, CZTS research focuses on discovering the secrets of material properties that hinder the efficiency of CZTS solar cells while branching out to develop alternative applications for this material. In this review, we summarize the interesting properties of CZTS as well as its promising applications, which include thin-film solar cells, charge-transfer layers in perovskite solar cells, and photoelectrochemical water splitting while briefly commenting on its other possible applications.

In the paper developments and some preliminary experiments concerning the application of thermographic phosphors for surface temperature and heat flux measurements in gas turbine combustion chambers are presented. When illuminated with W light (typically from a pulsed laser) these material exhibits phosphorescence, which is temperature dependent by Virtue of variations in the relative intensity of distinct emission lines or of variations in the time constant of the exponential emission decay which occurs once excitation has ceased. Both modes of sensitivity have been investigated with a range of phosphors including are YAG-:%, YAG:Dy and Y203:Eu. Of these YAG:Dy has been shown to be best suited to measurements in combustion chambers. It is sensitive to temperatures in the range 300 to 1500% emits light in the blue green region of the spectrum where blackbody radiation is relatively weak and exhibits both modes of sensitivity.In addition a number of techniques for laying down phosphor coatings on metal substrates are reviewed and an experimental investigation of two techniques is presented. Firstly, the use of chemical binders similar to those used in thermal paints and, secondly, a new cost effective coating technique refmed to as Electrostatic assisted Combustion Chemical Vapour Deposition (EACVD) which has been developed in the Materials Department at Imperial College. The latter allows thin layers of phosphors to be laid down without the need for a chemical binder and with close control of coating composition and thickness. To demonstrate the technique a 2pm thick layer of Y203:Eu has been laid down on a nimonic substrate and a performance comparison made with a similar coating laid down using the alternative chemical binder technique. The EACVD coating has been shown to be more robust than those laid down with chemical binders whilst the coating shows similar temperature sensitivity.

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